Expression of MHC antigens in normal human lungs and transplanted lungs with obliterative bronchiolitis.

Immunocytochemical techniques have been used to investigate the expression of common determinants of class I, common determinants of class II and DR, DP, and DQ antigens on frozen sections from twenty normal donor lungs, three lungs resected due to carcinoma and nine lungs removed from heart/lung recipients who were undergoing retransplant due to obliterative bronchiolitis. In all lungs, alveolar macrophages expressed common determinants of class I and class II, as well as DR, DP and DQ antigens. In normal lung, class I was expressed on all vascular endothelium, all tracheal epithelium and most, but not all, bronchiolar epithelium. Class II was always expressed on tracheal epithelium, but expression on bronchiolar epithelium and vascular endothelium was variable and sometimes absent. In lungs from transplant patients with severe obliterative bronchiolitis, vascular endothelium, in addition to expressing class I, now consistently expressed class II. Epithelium from trachea, bronchioles, and alveoli also consistently expressed class I and class II. To conclude, there is enhanced expression of class II antigens on endothelial and epithelial cells from lungs with obliterative bronchiolitis.